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Copper‐Free Asymmetric Allylic Alkylation with a Grignard Reagent: Design of the Ligand and Mechanistic Studies
Author(s) -
Grassi David,
Dolka Chrysanthi,
Jackowski Olivier,
Alexakis Alexandre
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201202318
Subject(s) - stereocenter , chemistry , regioselectivity , reagent , alkylation , tsuji–trost reaction , allylic rearrangement , enantiomer , bromide , organic chemistry , ligand (biochemistry) , combinatorial chemistry , enantioselective synthesis , medicinal chemistry , catalysis , biochemistry , receptor
The Cu‐free asymmetric allylic alkylation, catalysed by NHC, with Grignard reagents is reported on allyl bromide derivatives with good results. The enantioselectivity was quite homogeneous (around 85 % ee ) on large and various substrates, regardless of the nature of the Grignard reagent. The formation of stereogenic quaternary centres was highly regioselective for both aliphatic and aromatic derivatives with good enantiomeric excess (up to 92 % ee ). The methodology developed was found to be complementary with the Cu‐catalysed version. Several new NHCs were tested with improved efficiency. In addition, mechanistic studies, using NMR spectroscopy, led to the discovery of the catalytically active species.